Abstract: An ultramicro circuit board based on an ultrathin adhesiveless flexible carbon-based material and a preparation method thereof. The method comprises the steps of: S1. depositing to form a PI film on a surface of a quantum carbon-based film through a chemical vapor deposition (CVD) reaction, and manufacturing a flexible circuit board base material with a quantum carbon-based film/PI double-layer composite structure; and S2. manufacturing a high-frequency ultramicro circuit antenna on the flexible circuit board base material through a laser scanning etching method. The preparation method has the advantages of being good in environmental friendliness, high in efficiency, low in manufacturing cost and the like, and the manufactured antenna ultramicro circuit board has the advantages of being high in thermal and electrical conductivity, ultra-flexible, low in dielectric, low in loss and high in shielding performance, which can be applied to 5G equipment.